Once upon a time, Donald Trump owned a bunch of casinos, so Las Vegas should be kind of home turf for him when he takes the stage at 9 p.m. ET Wednesday for the third and final presidential debate against Hillary Clinton. The debate is being hosted by the University of Nevada, Las Vegas, where student attendance is being limited to undergraduates with a C average or better and graduate students with a grade average above a B.

Here are some things we are watching for:

'Rigged'

It is clear that Trump's closing argument in this campaign is that if he loses, it is because the system is rigged against him. During the first debate, he noted there was a problem with his microphone; during the second debate, he said the moderators were aligned against him. "It’s nice — it’s one on three." Since the debate moderator this time is Chris Wallace of Fox News, it is less likely Trump will claim the moderator is biased against him. But he will no doubt bring back his charge that Clinton, the media, and even Republican leaders like Speaker Paul Ryan are ganging up to try deny him the White House.

(Just like to point out here that in August, I said in this Facebook Live video that we would be hearing "more and more and more about the 'rigged system' ... that is becoming the theme of the 2016 election cycle." Every now and then, I get one right.)

WikiLeaks

The steady stream of emails hacked from the account of Clinton campaign chairman John Podesta and released by WikiLeaks over the past few days have offered a host of embarrassments for Democrats. There were emails suggesting Clinton got a heads-up on questions being asked by CNN; emails showing staff disparaging Catholic voters; and emails suggesting that the government of Qatar — which Clinton had accused of supporting terrorists — was donating $1 million to the Clinton Foundation in honor of Bill Clinton's birthday.

Trump has claimed that the media has ignored these stories, and he does have a point. The stream of stories about Trump's alleged sexual misconduct with women has essentially drowned out coverage of the leaks, which otherwise would likely be front-page news. Wednesday will be Trump's last chance to confront Clinton directly about these issues.

The Wall

It is interesting how little of the first two debates had to to with immigration, one of the defining issues of Trump's campaign. We should get more on that topic in Vegas. Wallace has announced that immigration will be one of the six topics covered during the debate. The other five:

Note that this is a moderator-only debate, not a town hall like the last one, which featured questions from the audience, though we would not be surprised to see some kind of question from social media or via video.

Remember the swing states

People tend to get all excited on debate nights about insta-polls on who won. We encourage you to ignore all that.

With three weeks to go until the election, all that really matters now are Florida, North Carolina, Ohio and Pennsylvania. Trump basically has to win all four of these states to have any chance of winning the White House. Heading in to the debate, Clinton holds leads in the polls in Florida, Pennsylvania and North Carolina, according to USA TODAY's trusty Poll Tracker, powered by RealClearPolitics.

The question on Thursday morning will be: Did Trump do enough Wednesday night to turn the tide on those critical states?

Trick or Treat

With Halloween less than two weeks away, Trump is clearly winning the costume wars. By all accounts, Trump masks and costumes are far outselling Clinton masks and costumes. But perhaps a third party, such as red-sweatered Ken Bone, star of the second debate, is keeping Clinton from closing the gap.